1. Field of the Invention
The present invention is related to reactive material enhanced projectiles and, more particularly, to projectiles including incendiary or explosive compositions, the projectiles having improved stabilization characteristics and control over the ignition of the composition.
2. State of the Art
There are numerous designs of projectiles containing incendiary or explosive compositions. Such projectiles are conventionally configured such that the incendiary or explosive composition becomes ignited upon, or shortly after, the projectile's contact with a target. Ignition of the incendiary or explosive composition is intended to inflict additional damage on the intended target. Aside from the additional damage that might result from the pressure of the explosion, the burning of the composition, or both, often, ignition of the incendiary or explosive composition is accompanied by fragmentation of the projectile casing thereby providing additional shrapnel-like components which spread out to create a larger area of impact and destruction.
Some exemplary projectiles containing an incendiary or explosive composition are described in U.S. Pat. No. 4,419,936 to Coates et al., the disclosure of which is incorporated by reference herein in its entirety. The Coates patent generally discloses a ballistic projectile having one or more chambers containing a material which is explosive, hypergolic, incendiary or otherwise reactive or inert. The material may be a liquid, a semi-liquid, a slurry or of solid consistency. Initially, the material is hermetically sealed within a casing of the projectile but is released when the projectile impacts with a target and the projectile casing is concomitantly fragmented.
In many cases, projectiles containing an incendiary or explosive composition are designed to provide increased penetration of the projectile into a given target such as, for example, an armored vehicle. One such projectile is the MK211 armor piercing incendiary (API), a projectile which is configured for penetration of armor plating. However, the MK211 and similar projectiles have proven to be relatively ineffective against what may be termed thin-skinned targets. Thin-skinned targets may include, for example, liquid filled fuel tanks or other similar structures having a wall thickness of, for example, about 6 millimeters (mm) (about 0.25 inch) or less.
Use of conventional APIs or other projectiles configured for penetration of armored structures often fail to inflict any damage on thin-skinned targets other than the initial penetration opening. This is often because the projectiles are configured as penetrating structures with much of the projectile being dedicated to penetrating rods or other similar structures. As such, these types of projectiles contain a relatively small amount of incendiary or explosive composition therein because the volume needed for larger amounts of such material is consumed by the penetrating structure. Thus, containing relatively small amounts of incendiary or explosive materials, the resultant explosions or reactions are, similarly, relatively small. Additionally, because the incendiary or explosive composition is configured to ignite substantially simultaneously with the impact of the projectile and a target, the explosion or other reaction is often complete before it can inflict substantial additional damage to the target (such as ignition of leaking fuel from a fuel tank).
An exemplary projectile designed for discrimination between an armored-type target and a thin-skinned target includes that which is described in U.S. Patent Application Publication Number 20030140811. The projectile disclosed by this publication includes one or more sensors, such as a piezoelectric crystal, which are configured to determine the rate of deceleration of the projectile upon impact with a target. The rate of deceleration of the projectile will differ depending on whether an armored-type target or a thin-skinned target is being struck. For example, the rate of deceleration of the projectile will be relatively greater (i.e., it will decelerate more quickly) if the projectile strikes an armored target than if it strikes a thin-skinned target. Upon determining the rate of deceleration, a fuse will ignite an incendiary or explosive composition at an optimized time in order to effectively increase the damage to the specific target depending on what type of target is being impacted.
While the projectile disclosed in the US 20030140811 publication reference provides an incendiary or explosive projectile which may provide some effectiveness against thin-skinned targets, the projectile disclosed thereby is a complex structure requiring numerous components and would likely be expensive and difficult to fabricate.
An additional problem with conventional incendiary or explosive projectiles is the ability to control the projectile's stability and accuracy. For example, considering the projectile disclosed by the above-described Coates patent wherein the incendiary/explosive material is in the form of a liquid, the liquid and surrounding casing will likely exhibit differing angular velocities at any given time, particularly when the casing is rapidly changing its angular velocity such as upon initial firing or upon initial impact of a target. The independent angular velocities of the liquid material and casing can affect the overall stability of the projectile during flight and, ultimately, affect the projectile's accuracy, particularly over long ranges. Of course, such discrepancy in angular velocities can occur when other incendiary or explosive compositions, including solid compositions, are housed within the projectile's casing.
In view of the shortcomings in the art, it would be advantageous to provide a projectile comprising a reactive material in the form of an incendiary, explosive or pyrotechnic composition wherein the projectile may be tailored for proper ignition of the reactive material contained therein depending on the nature of an intended target while maintaining a simple, robust and yet relatively inexpensive structural design. Additionally, it would be an advantage to provide an explosive or incendiary projectile which exhibits increased stability and accuracy.